In the production of thermal micro-fluid ejection devices such as ink jet printheads, a cavitation layer is typically provided as an ink contact layer for a heater resistor. The cavitation layer prevents damage to the underlying dielectric and resistive layers during ink ejection. Between the cavitation layer and heater resistor there are typically one or more layers of a passivation material to reduce ink corrosion of the heater resistor. As ink is heated in an ink chamber by the heater resistor, a bubble forms and forces ink out of the ink chamber and through an ink ejection orifice. After the ink is ejected, the bubble collapses causing mechanical shock to the thin metal layers comprising the ink ejection device. In a typical printhead, tantalum (Ta) is used as a cavitation layer. The Ta layer is deposited on a dielectric layer such as silicon carbide (SiC) or a composite layer of SiC and silicon nitride (SiN). In the composite layer, SiC is adjacent to the Ta layer.
One disadvantage of the multilayer thin film heater construction is that the cavitation and protective layers are less heat conductive than the underlying resistive layer. Accordingly, such construction increases the energy requirements for a printhead constructed using such protective layers. Increased energy input to the heater resistors not only increases the overall printhead temperature, but also reduces the frequency of drop ejection thereby decreasing the printing speed of the printer. Hence, there continues to be a need for printheads having lower energy consumption and methods for producing such printheads without affecting the life of the printheads.